Older adults, particularly those caring for impaired loved ones (family caregivers), are at substantial risk for inactivity and sub-optimal dietary patterns. The physiological impact and resultant reductions in chronic disease risk obtained by enhancing both of these key health behaviors have been increasingly recognized. Yet, the best methods for combining the two to optimize behavioral success, with respect to sustained improvements in physical activity and healthful dietary intake, remain unclear. Two general temporal approaches have been utilized to date: a Sequential approach that emphasizes shaping of positive experiences in one health behavior prior to introducing the second behavior (learning theory perspective); and a Simultaneous approach that focuses on the benefits that can be more rapidly gained by introducing both behaviors concurrently (a 'life change' perspective). No systematic comparison of these two approaches in influencing sustained physical activity and dietary change currently exists. The objective of this study is to compare these alternative approaches by conducting a randomized controlled trial to evaluate the effects of a 12-month telephone-supervised, home-based physical activity + dietary intervention, conducted in either a sequential or simultaneous fashion, on physical activity and dietary patterns. Older adult caregivers (N=240) who are under-active and have sub-optimal diets, will be randomly assigned to one of three programs or to an attention-control arm. The four arms will be matched with respect to amount and type of staff contact. Data will be collected at baseline, 4, 8, and 12 months using appropriate physical activity, dietary, physical performance, and quality of life measures. Our primary hypotheses are that (1) caregivers assigned to the experimental arms will show greater 12-month improvement in both behaviors than controls, and (2) those randomized to one of the two Sequential exercise + diet programs will show greater improvements in the two behaviors relative to adults assigned to the Simultaneous program, due to the greater mastery and lower level of stress engendered by this 'smaller steps' approach. Additional questions of interest include evaluation of potential mediators and moderators of the interventions, and intervention related effects on physical functioning and health-related quality of life. This study will contribute important theoretical and public health information concerning how best to combine physical activity and dietary behaviors to optimize sustained adherence and promote desirable health outcomes.